![]() Next step is to actually apply our migrations using flask db upgrade command. The previous step just created the migration file. More information about commands can be found here. In case you haven’t changed any schemas and there isn’t anything for autogenerate to detect, but you still want to create a new migration, it’s possible to do so by creating an empty revision script. When it comes to more complex migrations, alembic autogenerate is often a good place to start, however, you might have to edit migration files and add things to it depending on what you want to achieve. However, alembic autogenerate feature has some limitations. Alembic is good at simple migrations like creating tables, adding/renaming columns etc. You are free to customize these migration files as needed. Each migration file get its own Revision ID, which is a unique identifier for this particular migration. Each migration file has an upgrade function for applying the migration, and a downgrade function in case you want to rollback. Notice that Alembic automatically created the needed SQL for creating a table based on the Post model we defined earlier. Now you should find a new migration file under migrations/versions/. Migrate/migrations/versions/da0e365b163c_.py. ![]() INFO Detected added table 'post' Generating /home/kim/projects/blog-code/flask-database-migrations-using-flask. Since we have now created our first database model, Alembic detects that a table for that corresponding model should be created. This will create a new migration file for any database schema changes you have made. Since we already created our first database model Post, we can also generate our first migration using flask db migrate command. done Please edit configuration/connection/logging settings in '/home/kim/projects/blog-code/flask-ĭatabase-migrations-using-flask-migrate/migrations/alembic.ini' before proceeding.Īfter running the initalization command, you should be able to see something similar to this. done Generating /home/kim/projects/blog-code/flask-database-migrations-using-flask. done Creating directory /home/kim/projects/blog-code/flask-database-migrations-using-flask. Let’s start of with defining the needed dependencies by creating a requirements.txt file.Ĭreating directory /home/kim/projects/blog-code/flask-database-migrations-using-flask. I will show how to auto-generate migrations, how to apply migrations, how to downgrade, and how to automatically migrate the database when deploying your Flask application using Docker (bonus part). We will create a simple application with a database table for posts. ![]() ![]() Now I will show how Flask-Migrate can be used in Flask applications. Using a database migration tool, you are able to easily upgrade or downgrade database changes, or even rebuild your database. This is truly powerful, since it enables you to have a single source of truth and a history of your database changes in source control. It can automatically generate migration files based on database schema models, and apply those migrations to databases. Alembic is the migration tool that actually takes care of database migrations under the hood. Flask-Migrate is a python package that configures SQLAlchemy and Alembic for your Flask application.
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